27 Apr The Basics of Recording Audio in a Controlled Environment for Digital Video
Hello, Internet surfers. Today I’m going to talk about how to record audio (voice talent) for digital video in a controlled environment. By controlled environment, I am referring to a soundstage or a studio versus field recording or an uncontrolled environment outdoors or on location. Even in a studio there are quite a few variables to consider before creating your next masterpiece. Let’s look at a few of the options to consider before turning on your camera.
1. Recording Direct-to-Camera or to an External Recorder
When recording directly into your camera, you first have to determine how your camera accepts audio. Most digital cameras have built-in microphones that will vary in quality depending on the brand and price of the camera. Internal microphones can work well in the right situation – usually when the subject is close to the camera – but lack overall flexibility. If the built-in microphone doesn’t work for your project then you should explore external microphone options.
1/8-inch connections. Size of headphone jack for a computer or phone.
The most common built-in inputs for external microphones are 1/8-inch unbalanced minijacks or XLR-balanced inputs. Considered consumer-grade, 1/8-inch inputs are a big advantage in price when choosing a microphone or camera. The disadvantage is that there aren’t as many microphone options and they are considered to have a higher noise level and lower sound quality than XLR inputs.
Balanced XLR cable.
XLR inputs are considered professional-grade. They accept regular 3-pin balanced low-impedance microphone cables. This offers more flexibility in microphone choice, length and durability of cables and higher sound quality. Both 1/8-inch and XLR cable inputs can accept phantom power if supported by the camera. (More about phantom power later.)
Your camera will dictate how you can connect your microphone. You can also get an XLR adapter if you have a 1/8-inch input.
The biggest advantage to recording directly to the camera is that you are always ready to shoot, plus there is time saved during editing. The audio is automatically synced to the video. You do not have to resync the audio with the video in post-production, which can be beneficial when creating video quickly or in a live environment. Logging video or internal editing is also much easier with the audio directly recorded. This works best in a single-microphone environment.
Recording to an External Recorder
Recording externally is ideal in the following situations:
- When using multiple microphones or cameras.
- If you have limited disk space on your memory card.
- If you prefer using a higher-quality preamp or mixer for your audio.
If you have multiple microphones or cameras, you can easily record with multitracks into an external device. This gives you more options and control in post-production. If the quality of the audio file is paramount, you can record audio uncompressed and at a higher sample/bit rate externally than you can directly because of file size restraints. Processing your microphone through a mixer or preamp will also give you a much cleaner sound than that found built into the camera.
Editing time is usually longer and file management is a bit more complicated when recording to an external device. Audio/video syncing software like Red Giant PluralEyes has greatly increased the speed of post-production compared to syncing audio with a clapper, but it still isn’t as time-efficient as recording straight to the camera. These are the main differences between recording audio direct-to-camera versus using an external recorder.
2. Microphone Selection
There is a veritable cornucopia of microphones available today. How can you possibly choose? Let’s narrow it down with a brief description of different microphone characteristics.
Wireless or Wired?
Wireless microphones are usually used with lavalier (lapel) microphones. When using wireless, you are not bound by a cable and are free to move as you wish. The drawbacks are potential interference and lower sound quality than wired microphones. High-quality, low-interference microphones come at a high price. If budget isn’t a concern and you want to use a lavalier, then go wireless; otherwise, use a cable.
Wireless lavalier microphone can clip onto talent’s clothes for inconspicuous recording of audio.
Stationary, Lavalier and Shotgun Microphones
A stationary large diaphragm condenser or ribbon microphone is usually set on a desk in the shot. They are commonly seen on talk shows since they can pick up sound on both sides of the mic equally. Most have superior clarity, richness and sensitivity compared to other microphones, but they can pick up a lot of ambient noise. If used, they are commonly in conjunction with a shotgun boom mic or lavalier.
A lavalier microphone is a good option for picking up voice if the subject wants to move freely and not think about mic placement or the microphone’s sweet spot. These are usually wireless. They are easy to conceal on a dark piece of clothing or can be left in sight. Lavs do not pick up much ambient sound due to their close proximity to the audio source and polar pattern design. The main drawbacks are potential body noise when brushed by the talent and lower sound quality than other options.
Another studio microphone option is a shotgun or boom mic. Shotgun microphones sit out of the shot and point at the subject. They are very directional and have better sound quality than most lavaliers, but not as rich as large diaphragm microphones. They also will pick up slightly more ambient sounds than a lavalier. These mics can be mounted to a boom if the subject is stationary, or the crew can hold it and move with the subject. A shotgun has a sweet spot of a couple of feet away from the audio source which can offer freedom from having a lavalier attached to one’s body, especially if body noise is a concern. The drawback is that the talent has to stay on their mark unless the microphone is manned.
All of the mentioned microphones can be used independently or in conjunction with one another to get your desired sound. Your room and application are often the key factors to this choice.
Condenser, Dynamic and Ribbon Microphones
Condenser microphones are the most common microphones in the studio environment. They require power to function. This is called phantom power. Phantom power travels through the microphone cable from a power source like a mixer, preamp or camera to power the microphone. This works much in the same way as a USB connection powering an external device from a computer.
Neumann U87 large-diaphragm condenser microphone.
Condenser microphones have higher output and broader frequency response than dynamic mics. They pick up more subtleties but aren’t able to handle loud signals as well as a dynamic. Most condenser mics cost more than dynamic mics and they are more fragile.
Shure SM7B dynamic microphone.
Dynamic microphones do not require phantom power. They have lower output and frequency response compared to a condenser mic. They are best used with loud sources or in conjunction with a preamp that can boost their signal to reduce noise. Dynamic mics are generally the cheapest and most durable microphones available on the market.
AEA KU4 ribbon microphone.
Ribbon microphones are similar in sound to condenser microphones, but they have a more mellow or less harsh tone. They do not require power and can be damaged by phantom power and are considered very delicate. Ribbon mics are traditionally expensive and are thought of as vintage microphones because of their popularity in the beginning of radio and TV broadcasting, but are still manufactured today. They have excellent tone and can pick up very subtle sounds and ambient noise depending on their polar pattern.
The polar pattern of a microphone is the directionality or area of focus in which it picks up sound waves. There are three basic polar patterns: cardioid, omnidirectional and figure-of-eight (bidirectional). There are three additional subpatterns: supercardioid, half-cardioid and hypercardioid. Each pattern is useful in different environments depending on what sounds you want to pick up. Some microphones have multiple polar pattern adjustments. I will highlight the most common polar patterns and their uses below.
Cardioid polar patterns are more sensitive in the front of the mic and less sensitive in the back. These work well when you want a tighter focus on the subject and less ambient noise.
Supercardioid polar patterns have a narrower field of range in front than a regular cardioid. They reject ambient noise better but slightly pick up sound directly behind them. These are ideal to get tight focus on a subject if there is proper acoustic dampening behind the mic.
Omnidirectional polar patterns pickup sound equally from all directions. They have a broader field of range. Lavalier microphones are generally omnidirectional since they are below the audio source.
Figure-of-eight polar patterns pick up what is directly in front of them and what is directly behind them equally. They reject the sound on the sides. These are usually on large diaphragm condenser and ribbon microphones.
Shotgun microphones have their own polar pattern, but are closest to having a hypercardioid polar pattern. This means they are extremely focused and reject all directions in which they are not pointed. They have a much tighter focus field than cardioid or supercardioid microphones.
Shotgun microphone has a very narrow polar pattern.
3. Microphone Placement
Placing the microphone is a very important part of the process. Any time you set up a shot, the microphone should be monitored with headphones to find the “sweet spot.” The sweet spot is the ideal area for the maximum effectiveness of the microphone in relation to the subject. If too close, the sound will be overly loud, distorted or boomy. If too far away, the sound will be too thin and pick up more ambient noise. No two people’s voices are the same in terms of tone, amplitude or phasing. The better sound you get in the beginning, the less you have to fix it in post-production, which can be a huge timesaver.
4. Room Acoustics
Room acoustics can play a major role in capturing a clean audio signal. Microphone polar patterns and the style of microphone – lavalier, shotgun, etc. – can help you get the best sound in a certain environment, but room acoustics also create nearly as much of the sound as the audio source. You don’t want to sound like you are in a cave or an institution. Dampening with tiles, diffusers, bass traps and other acoustic treatments can help tone down unwanted reverb, echo and distortion.
Resonant frequencies called “room modes” can reflect and reverberate certain frequencies that create standing waves (room ring) and have the potential to distort the audio source or cause feedback. Acoustic treatments can also help with this problem. In a worst-case scenario the use of equalization and noise gates can also help remedy unwanted room modes or ambient noise. It’s always best to attempt to get the cleanest source possible initially before relying on EQ.
5. Capturing Audio
If you aren’t going to record audio into your camera directly, you will need some kind of recording device. There are many portable and not-so-portable options available. Some of the popular devices used today are portable digital recorders (Zoom, TASCAM and Sony), laptop and desktop computers with recording applications, multitrack hard-disk recorders and even tablets and phones. Pick something reliable that you are comfortable using and back up to a hard drive or cloud storage. Remember, if you lose the audio you will have to reshoot the video.
TASCAM DR-60DmkII portable recorder.
6. Setting Levels and Monitoring
A good audio level will yield the cleanest possible signal. Ideally, you want to get the audio level as hot or loud as possible without clipping the channel. Clipping occurs when the signal is louder than zero decibels on the channel meter. This can create distortion or a fuzzy sound (think Black Sabbath guitars). This may sound cool on a guitar but not on your talent’s voice in a video. Tools such as a preamp or compressor/limiter used gently in line with the microphone can help get the best signal level. If you do not have any external processing, make sure you set the level to the highest peak without hitting in the red on the meter.
7. Mixing Audio
Once you have shot and recorded your project, the final touches need to be applied. Mixing the audio can be easy if the source material is good, or it can be a large task if preproduction was less than stellar. You can edit and mix your audio in a video editor like Adobe Premiere Pro or Final Cut Pro, or you can mix in a digital audio workstation like Pro Tools, Logic or Cubase.
Less is more. I prefer to remove any undesirable frequencies with EQ and put slight compression/limiting on the voice. There is a host of compression and EQ plug-ins that do the job quite well. Pick your favorites and apply as needed. If you are suffering from ambient noise like an air conditioner, mild hissing or crew members shuffling their feet, I found a great set-and-forget noise suppression plug-in: the Waves NS1. It is just one fader, so it is incredibly simple and easy to use. It isn’t a magic bullet but it does a good job on small problems.
I like to mix down and normalize the level to minus 1.5 decibels for safe measure. This is just my preference; you may prefer a different level. If the audio was recorded externally I’ll make sure the camera audio was recorded for syncing. When using a clapper, sync the camera audio to the clip from the clapper to the edited audio. I’ve been using PluralEyes lately to sync audio to video and find it to be a big timesaver. You are now ready to start editing your video!
So those are the basics of recording audio for digital video in a studio or controlled environment. There are many more details I could go into, but I’ll save those for another day. I hope this will come in handy for you. Feel free to contact me at firstname.lastname@example.org or leave a comment below if you have any questions or tips of your own that you would like to share.
Until next time.